?DESCRIPTION (provided by applicant): The structure and function of the vast array of microbial communities hosted by the human body (microbiome) is emerging as a novel contributor to variation in health outcomes. As links between the human microbiome and health emerge, population health approaches to understanding the social and environmental determinants of microbiome variation will be an important complement to microbiological and clinical research. Advances in massively parallel sequencing and computing now enable relatively low-cost characterization of the human microbiome in population-based studies. The Human Microbiome Project and MetaHIT project characterized the human microbiome among small groups of healthy volunteers, but neither of these projects used a representative population-based sample with a wide range of phenotypic variation, and the association of socioeconomic and demographic factors with microbiome composition is largely unknown. The human mouth harbors one of the most diverse microbial communities in the human body, which has been linked with both oral and systemic disease including diabetes, cardiovascular disease, and pre-term birth. This study will establish the prevalence of oral microbiome characteristics and the associations of these characteristics with sociodemographic factors in a large, nationally representative sample from the 2009-2012 National Health and Nutrition Examination Survey (NHANES). We will further examine the association of the oral microbiome with biomarkers of health risk that vary by SES and race/ethnicity including inflammation (C-reactive protein) and diabetes and pre-diabetes (fasting blood glucose and HbA1C%). Finally, the project will also build infrastructure for inter-disciplinary research in this emerging area by developing a publicly available, web- based interface and toolkit for population health researchers to easily incorporate microbiome data into their analysis. Understanding the social and life course determinants of the oral microbiome has the potential to lead to novel prevention strategies based upon environmental modification and manipulation of microbial ecology to reduce health disparities.